Backups are worthless if you don't know when they got in, restoring could just put back in the holes back in place.
Because DISH is a publicly held company and because of the financials involved they need to make sure everything is secure again. In addition I have heard that certain programmers won't let DISH's authorization servers connect to theirs for customers to login to to access streaming services until they are told that DISH's systems are safe and will not infect theirs.
This is a mess. And as an IT guy myself it's one of the biggest fears you could have working IT. I remember when SatelliteGuys was hacked and I was out at Sea on a cruise and we were hacked. I worked for 12+ hours and got it fixed back up again, and thankfully the hacker left clues so I was able to find another forum this happened to and got the fix and was able to patch everything back up. My internet bill was huge there was no flat rate then. But I couldn't just let it go for another 4 or 5 days while I was at Sea.
DISH has some very good it folks, I know and talk to them from time to time, it's a shame this happened to them. But hopefully they learned from this and can prevent something like this from taking down everything again in the future.